A method is known from DE 10 2012 015 846 A1 in which a modification of the surface geometry is produced by additional movements when dressing on the tool, said modification having a constant value in the generating pattern at least locally in a first direction on the tooth flank and being given by a function f(x) in a second direction which extends perpendicular to the first direction. This modification of the surface geometry of the tool is transferred to the workpiece by the diagonal generating method. A method is known from EP 1 995 010 A1 and WO 2010/060596A1 of dressing a worm in a crowning manner over its width during dressing by changes of the center distance. The center distance between the tool and the workpiece is furthermore changed in a crowning manner using this worm dressed in a crowning manner during machining of the workpiece. The superposition of the two modifications hereby produced should minimize the twisting which is determined on two tooth traces. A diagonal generating method is known from DE3704607 A1 in which a worm is used whose flank angles on the left and right flanks decrease from a maximum value at one end of the worm to a minimum value at the other end of the worm to compensate the twisting of a helix crowning produced by a center distance change in the diagonal generating method. Methods are known from DE 196 248 42 A1 and DE 197 068 67 A1 in which a worm whose profile angle changes over its width is produced by a constant change of the position of the dresser with respect to the tool during dressing. The constant change of position of the dresser is determined on the basis of a desired modification of the workpiece. Methods are likewise known from DE 10 2005 030 846 A1 and DE 10 2006 061 759 A1 in which a worm is manufactured by corresponding dressing kinematics either over its total width with a constantly modified profile angle or with the profile angle modified over the worm width. A two-flank dressing for twist-free generating grinding is known from Kapp, Effizient and produktiv mit technologischer Flexibilität, JOSE LOPEZ [Kapp, Efficient and Productive with Technological Flexibility, JOSE LOPEZ].
It is the object of the present disclosure to provide a method of producing a toothed workpiece which allows a greater flexibility in the specification of the desired modification of the surface geometry of the workpiece.
The present disclosure shows a method of producing a toothed workpiece having a modified surface geometry by a diagonal generating method by means of a modified tool. In a first variant, a tool is used whose surface geometry comprises a modification which can be described at least approximately in the generating pattern at least locally in a first direction of the tool by a linear and/or quadratic function, with the coefficients of this linear and/or quadratic function being formed by coefficient functions FFtC,1, FFtL,1 and/or FFtQ,1 in a second direction of the tool which extends perpendicular to the first direction. The first direction of the tool optionally has an angle ρFS not equal to zero with respect to the tool width direction. In a second variant which can optionally be combined with the first variant, a modification is used whose pitch and/or crowning varies in dependence on the angle of rotation of the tool and/or on the tool width position. This specific modification of the tool generates a corresponding modification on the surface of the workpiece by the diagonal generating method. Provision is made in accordance with the present disclosure that a desired modification of the surface geometry of the workpiece is specified, and a modification of the surface geometry of the tool suitable for producing this desired modification is determined in combination with a diagonal ratio of the diagonal grinding method suitable for producing the desired modification.
New possibilities of the specification of the surface geometry of the tool results by the present disclosure in comparison with the prior art, on the one hand, said possibilities correspondingly allowing additional possibilities on the specification of the desired modification of the surface geometry of the workpiece. The interaction between the surface geometry of the tool and the diagonal ratio of the diagonal generating method used for machining the workpiece is furthermore taken into account in accordance with the present disclosure and they are matched to one another such that the desired modification of the workpiece results. Since work is not carried out with a specified diagonal ratio, but this is rather determined in dependence on the desired modification of the surface geometry of the tool, a substantially increased flexibility results with respect to the surface geometries of the workpiece which can be manufactured by the method in accordance with the present disclosure.
The diagonal ratio is optionally set such that in the diagonal generating method the first direction of the tool is mapped onto a first direction of the workpiece suitable for producing the desired modification of the workpiece. The diagonal ratio is optionally determined by curve fitting and/or analytically.
In accordance with the present disclosure, the desired modification of the surface geometry of the workpiece can optionally be specifiable in a first variant as a modification or can comprise a modification which can be described at least approximately in the generating pattern at least locally in a first direction of the workpiece by a linear and/or quadratic function, with the coefficients of this linear and/or quadratic function being formed by coefficients FFtC,2, FFtL,2 and/or FFtQ,2 in a second direction of the tool which extends perpendicular to the first direction. This corresponds to the first variant of the surface geometry of the tool explained in more detail above.
In a second variant, the desired modification of the surface geometry of the workpiece can optionally be specifiable as a modification or can comprise a modification whose pitch and/or crowning varies in dependence on the workpiece width position. This can in particular correspond to the above-described second variant of the surface geometry of the tool. The two variants can here also be combined with one another.
The expanded possibilities with respect to the modification of the surface geometry of the tool thus allow additional possibilities in the desired modification of the surface geometry of the workpiece. The diagonal ratio is optionally selected such that the first direction of the modification of the tool is mapped to the first direction of the modification of the workpiece. The present disclosure takes account of the fact that the first direction of the modification of the tool can typically only be changed with difficulty and/or within certain limits. Greater possibilities thus result in the selection of the first direction of the modification of the workpiece by the additional matching of the diagonal ratio.
Provision is optionally made within the framework of the present disclosure that the coefficient functions FFtC,1, FFtL,1 and/or FFtQ,1 of the modification of the surface geometry of the tool are at least freely selectable within specific conditions to produce the desired modification of the surface geometry of the workpiece. This can in particular take place by a corresponding influencing of the dressing process of the tool.
Provision can alternatively or additionally be made that the coefficient functions FFtC,2, FFtL,2 and/or FFtQ,2 and/or the first direction of the modifications of the surface geometry of the workpiece are at least freely specifiable and/or selectable within specific conditions.
Alternatively or additionally, the pitch and/or the crowning of the modification of the surface of the tool can be at least freely selectable as a function of the tool width position within specific conditions. Data which determine the progression of the modification in the first direction in dependence on the tool width position can optionally be specifiable.
Alternatively or additionally, provision can be made that the pitch and/or the crowning of the modification of the surface of the tool can be at least freely selectable within specific conditions as a function of the workpiece width position. The pitch and/or crowning of the modification of the surface of the workpiece in the direction of a first direction can in particular be at least freely selectable within specific conditions as a function of the workpiece width position, with the first direction advantageously also being freely selectable within specific conditions.
The first direction of the modification of the surface geometry of the workpiece as well as data which determine the progression of the modification in the first direction in dependence on the workpiece width position can in particular optionally be specifiable.
Provision is optionally made that the diagonal ratio is determined in dependence on the first direction of the modification on the workpiece. As described above, this takes place in that a first direction which can be technologically produced is determined on the tool and the diagonal ratio is set such that the first direction on the tool is mapped onto the first direction on the workpiece.
Provision can be made in accordance with the present disclosure that the modification of the surface geometry of the tool is determined from the desired modification of the surface geometry of the workpiece by means of an inversion of an association function which describes the mapping of the surface of the tool onto the surface of the workpiece in diagonal generating grinding. This association function and its inversion depend on the selected diagonal ratio. The modification of the surface geometry of the tool suitable for producing the desired modification of the surface geometry of the workpiece and the diagonal ratio suitable for this can be determined in particular in that the diagonal ratio and the variable parameters of the modification of the surface geometry of the tool are varied within the framework of curve fitting to find a combination of modification of the surface geometry of the tool and diagonal ratio which approximates the desired modification as closely possible. With a relatively large class of functions, a substantially exact determination is even possible.
The determination optionally takes place using a function which analytically describes the mapping of the surface of the tool onto the surface of the workpiece in diagonal generating grinding. The above-described association function can in particular be able to be illustrated analytically.
In accordance with the present disclosure, the desired modification of the surface geometry of the workpiece can be specified as a continuous function and/or on a scatter plot. The continuous function can optionally be specified on a surface on the tooth flank and/or the scatter plot can span a surface on the tooth flank. The present disclosure is thus not restricted only to specifying the desired modification at one or more lines or points of the surface, but can be specified over a surface, in particular over the total surface of the tooth flank.
The modification of the surface geometry of the tool is optionally determined as a continuous function and/or on a scatter plot. The continuous function is optionally specified on a surface on the tooth flank and/or the scatter plot spans a surface on the tooth flank. The modification of the surface geometry of the tool can in particular be determined over the total tooth flank either as a continuous function or on a corresponding scatter plot.
In a possible embodiment of the present disclosure, the modification of the surface geometry of the workpiece at at least two or three rolling angles can be specifiable and/or selectable as a function of the tool width position, with interpolation taking place for the rolling angle regions disposed therebetween. Provision can furthermore be made that the modification of the surface geometry of the tool is variable within the framework of the determination and/or specification at at least two or three rolling angles as a function of the tool width position and interpolation takes place for the rolling angle regions disposed therebetween. If curve fitting and/or a distance function is/are used for determining the suitable surface geometry of the tool, the curve fitting optionally takes place over the total flank and thus also over the interpolated range and not only over the two or three rolling angles at which the modification is variable as a function of the tool width position.
The method in accordance with the present disclosure can in principle also be used with non-dressable tools, in which the corresponding modification of the surface geometry is produced during the production process and is fixedly specified during the machining procedure of the workpiece.
If it is a non-dressable grinding tool, the modification in accordance with the present disclosure of the surface geometry can be produced during the manufacturing process in exactly the same way as described in the following for dressable tools, with the only change being that instead of a dressing tool, a corresponding manufacturing tool is used, for example a rolling die.
For the case that the tool is a hobbing cutter, it has to be manufactured in such a way that the enveloping body of the hobbing cutter has the modification provided in accordance with the present disclosure. With respect to a hobbing cutter, the term “modification of the surface geometry of the tool” as used in the context of the present disclosure is to be understood as a modification of the surface geometry of the enveloping body of the hobbing cutter.
The present disclosure is, however, particularly used with dressable tools. In particular, the modification of the surface geometry of the tool is generated during the dressing process.
For dressable tools, provision is optionally made that the modification of the surface geometry of the tool is produced by the modification of a relative position between the tool and the dresser during dressing, with the dresser optionally being in line contact with the tool during dressing and/or the first direction of the modification of the surface geometry of the tool corresponding to the line of action of the dresser on dressing the tool and/or being specified by it.
The dressing takes place on two flanks in a first embodiment. This can in particular take place when the surface geometry of the tool is to be given a modification by the dressing which can be described at least approximately on both flanks in the respective generating pattern at least locally in a first direction of the tool by a constant or linear function, with the coefficients of this linear function being formed in a second direction of the tool which extends perpendicular to the first direction by coefficient functions FFtC,1 for the constant portion and FFtL,1 for the linear portion. This can alternatively or additionally take place when the surface geometry of the tool is to obtain a modification on both flanks in each case by the dressing whose tooth thickness and/or pitch varies in dependence on the angle of rotation of the tool and/or on the tool width position or whose crowning does not vary in dependence on the angle of rotation of the tool and/or on the tool width position.
The dressing takes place on only one flank, in contrast, in a second embodiment. This can in particular take place when the surface geometry of the tool is to obtain a modification by the dressing which can be described at least approximately in the generating pattern at least on one flank locally in a first direction of the tool by a quadratic function, with the coefficients of this quadratic function being formed in a second direction of the tool which extends perpendicular to the first direction by coefficient functions FFtC,1 for the constant portion and FFtL,1 for the linear portion and/or FFtQ,1 for the quadratic portion and/or whose crowning varies on at least one flank in dependence on the angle of rotation of the tool and/or on the tool width position. The dressing on one flank can also be useful if the pitch on the right flank deviates too much (e.g., deviates more than a threshold amount) from the negative value of the pitch on the left flank or if a two-flank dressing is not possible for other reasons, e.g. because no suitable dresser is available.
In accordance with the present disclosure, the relative position of the dresser to the tool during dressing with line contact can be specifically set such that the contact line between the dresser and the tool on the dresser is displaced in order hereby to influence the active profile transferred to the tool along the contact line, which in turn produces the desired modification on the tool. The pitch and/or crowning along the contact line on the tool can in particular be set or varied. This contact line on the tool optionally defines the first direction of the modification on the tool.
In general, the pitch of the specific modification of the tool in the context of the present disclosure is understood as the pitch in a first direction of the tool which includes an angle ρF1 other than zero with respect to the tool width direction and which in particular has a portion in the profile direction, i.e. the pitch of the modification corresponds to the profile angle difference.
Furthermore, a crowning of the modification of the tool in the context of the present disclosure is understood as a crowning in a first direction which includes an angle ρF1 other than zero with respect to the tool width direction and which in particular has a portion in the profile direction, i.e. the crowning of the modification corresponds to a profile crowning.
Since the direction of the line of action of the dresser on the tool during dressing and thus the first direction of the modification of the surface geometry of the tool can, however, not be changed to any desired extent, the first direction of the modification of the surface geometry of the tool is at least not freely selectable over a larger region. In accordance with the present disclosure, this requires a corresponding matching of the diagonal ratio to be able to select the first direction of the modification of the surface geometry over a larger region.
The pitch in a first direction of the workpiece which includes an angle ρF2 to the workpiece width direction is furthermore understood as the pitch of the specific modification of the workpiece in the context of the present disclosure, with the angle ρF2, however, also being able to be zero, but optionally not being equal to zero. A crowning in a first direction is furthermore understood as a crowning of the modification of the workpiece in the context of the present disclosure, with the angle ρF2, however, also being able to be zero, but optionally not being equal to zero.
The tools is optionally dressed in a modified manner by means of a profile roller dresser or a form roller. The profile roller dresser or the form roller in accordance with the present disclosure can in particular be rotatable about an axis of rotation and can have a rotationally symmetrical profile.
In accordance with a first variant, the profile roller dresser or form roller dresser can be in contact with the tooth of the tool during the dressing from the root region to the tip region so that the modification takes place over the total tooth depth in one stroke. A particularly fast dressing method hereby results.
In a second variant, the profile roller dresser or the form roller can only be in contact with partial regions of the tooth of the tool between the root and the tip during dressing so that the specific modification takes place over the total tooth depth in a plurality of strokes and with a respectively different relative positioning of the dresser and/or with different dressers and/or using different regions of a dresser. The dressing method is admittedly hereby prolonged. However, more variations in the selection of the surface geometry of the tool are possible since the modifications of the surface geometry in accordance with the present disclosure can be selected separately for each stroke. The dressing optionally still takes place in line contact, however, so that a relatively efficient dressing method still results.
Independently of the selected variant, the modification of the surface geometry of the tool is optionally produced in that the position of the dresser with respect to the tool during dressing varies in dependence on the angle of rotation of the tool and/or on the tool width position, with the production of the specific modification on the tool taking place in that at least three degrees of freedom are used in the relative positioning between the dresser and the tool for producing the desired modification. Four or even five degrees of freedom may be used. The degrees of freedom are optionally settable independently of one another for producing the desired modification.
Provision can in particular be made that at least three, four or all of the following five degrees of freedom are used for producing the specific modification on the tool: angle of rotation of the tool; axial position of the tool; y position of the dresser; center distance; and/or axial cross angle.
The axial position of the tool, i.e. the tool width position, is optionally used to displace the contact line of the dresser on the tool. Two, three of four degrees of freedom of the remaining four degrees of freedom may be set independently of one another to produce the specific modification along the contact line.
Provision can be made in accordance with the present disclosure that a desired modification of the surface geometry of the workpiece is specified, wherein suitable coefficient functions FFtC,1, FFtL,1 and/or FFtQ,1 of the surface geometry of the tool and a suitable diagonal ratio are determined in dependence on the desired modification of the surface geometry of the workpiece.
In this respect, in dependence on the desired modification of the surface geometry of the workpiece, a suitable variation of the position of the dresser with respect to the tool during dressing is optionally determined in dependence on the angle of rotation of the tool and/or on the tool width position and a suitable diagonal ratio is determined. The suitable variation of the position of the dresser with respect to the tool during dressing is in particular determined such that the desired geometry respectively results along the first direction of the tool which is determined by the contact line of the dresser. The diagonal ratio is then selected such that the first direction of the tool is mapped onto the first direction of the workpiece.
A desired orientation of the modification of the surface geometry of the tool can furthermore be specified in accordance with the present disclosure and the diagonal ratio can be set such that the desired orientation of the modification results during diagonal generating machining.
In accordance with the present disclosure, the diagonal ratio can be kept constant in a first variant at least over every stroke. This corresponds to a constant first direction of the modification over the total workpiece width.
In accordance with a further development of the present disclosure, the diagonal ratio can be changed within the framework of the machining of a workpiece. This makes possible a still greater flexibility with respect to the design of the machining method, the achievable modifications and the taking into account of technical production aspects.
In accordance with the present disclosure, it is possible to work with different diagonal ratios to machine different regions of the workpiece and/or on the use of different regions of the tool.
The different diagonal ratios can be used during the same machining stroke and/or different strokes can take place with different diagonal ratios.
In accordance with the present disclosure, it is possible to work with different diagonal ratios on the use of different regions of the tool for machining the same region of the workpiece. Different diagonal ratios can in particular be used for different strokes which are used for machining the same region. In a possible embodiment of the present disclosure, however, work is here also respectively carried out with a constant diagonal ratio within the respective regions.
Alternatively or additionally, work can be carried out with different diagonal ratios to machine different regions of the workpiece. In this respect, the diagonal ratio can be varied, while the width of the gear is moved over as part of the gear manufacturing machining. In accordance with an embodiment of the present disclosure, work can be carried out in each case with a constant diagonal ratio within the respective regions.
In this respect, the change of the diagonal ratio can in particular be used to vary the orientation of the modifications resulting on the workpiece. In this respect, in the diagonal generating method, the modified surface of the tool is mapped onto the surface of the workpiece, with this mapping depending on the selected diagonal ratio. A different orientation of the modification in different regions of the workpiece can thus be achieved by the variation of the diagonal ratio during the machining of these different regions of the workpiece.
If work is carried out in two or more regions in each case with a constant, but different diagonal ratio, different orientations of the modifications accordingly result, but are constant within the regions. If, in contrast, the diagonal ratio is varied within a region, a corresponding variation in the orientation of the modification results. If the diagonal ratio is given by a steady, non-constant function, a steady variation in the orientation of the modification accordingly results.
The present disclosure is therefore not restricted to the use of respective constant diagonal ratios for specific regions. The variations of the diagonal ratio can rather go beyond such a region-wise constant variation.
In accordance with the present disclosure, the diagonal ratio can be varied during the machining of the workpiece in dependence on the axial feed of the workpiece and/or of the tool. The diagonal ratio may be given as a continuous, non-constant function of the axial feed at least in a region of the axial feed. The diagonal ratio can in particular be freely specifiable in dependence on the axial feed. A variation of the diagonal ratio may be used while a modified region of the tool is used for machining the workpiece.
In accordance with one exemplary embodiment of the present disclosure, the progression of at least one line of the modification on the workpiece is specified along which the modification is given by a linear and/or quadratic function and the variation of the diagonal ratio is determined from this in dependence on the axial feed and in particular the continuous, non-constant function by which it is given. The non-constant progression of the diagonal ratio allows such modifications also to be produced on the workpiece in which the lines are curved on which the modification is given by a linear and/or quadratic function.
The variation of the diagonal ratio in accordance with the present disclosure can be used both with cylindrical tools and with conical tools. The use of conical tools will be described in even more detail in the following.
The tool in accordance with the present disclosure can have at least one modified region and one non-modified region in a first variant. In this respect, the tool optionally has two modified regions between which a non-modified region lies. If two modified regions are provided, the orientation of the modifications and in particular the first direction of the modifications can be identical in these regions. A particularly simple dressing method hereby results. Work is then optionally carried out with different diagonal ratios in the two modified regions in order hereby to achieve a different orientation of the modification on the workpiece.
In a second variant, the tool can have two regions having different modifications. The modifications can in particular have different orientations, in particular different first directions. Even greater degrees of freedom hereby result in the production of differently oriented modifications on the workpiece.
The second variant can furthermore also be combined with the first variant in that, in addition to the two regions having different modifications, a non-modified region is provided which can in particular be arranged between the two modified regions.
If a plurality of modified regions are provided, the modifications in the two regions can differ with respect to the coefficient functions of the modification in the second direction.
Tools modified in accordance with the present disclosure can in particular be used to carry out different modifications on different regions of the workpiece, for example to produce different reliefs, and in particular differently oriented end reliefs, at the upper edge and lower edge.
In an alternative embodiment of the present disclosure, the tool can have at least two regions which are used successively for the machining of the same region of the workpiece. The two regions can in particular be a rough machining region and a fine machining region. The rough machining region is used to achieve a greater material removal with a smaller precision. The fine machining region is, in contrast, used after the rough machining to improve the quality of the surface geometry.
In this respect, the machining steps within the different regions are advantageously carried out with different diagonal ratios. Work can in particular be carried out with a different diagonal ratio in the rough machining step than in the fine machining step. The diagonal ratios during the respective machining steps can in contrast be kept constant.
The use of different diagonal ratios in the two tool regions allows the given tool width to be used better. In this respect, in particular one of the two regions can be shorter than the other region although they are used for machining the same workpiece. Accordingly, in this example, only the diagonal ratio has to be adapted to the respective width of the machining region of the tool.
The regions used for machining the workpiece optionally use the total tool width.
In one embodiment of the present disclosure, however, at least the fine machining region is modified. Depending on the size of the modification, the rough machining region, in contrast, does not necessarily have to be modified. It can, however, likewise be modified.
If both regions, and in particular both the rough machining region and the fine machining region, are modified, the modifications each have a different orientation in a possible embodiment. In this respect, the modification which is to be produced on the workpiece by the two regions is naturally the same in each case. However, identical modifications in the two regions would be mapped differently onto the workpiece due to the respective different diagonal ratios. The modifications therefore may be differently oriented in the two regions so that they are each mapped on the same direction on the workpiece while taking account of the different diagonal ratio. In this respect, a non-dressable tool can in particular be used since there is greater freedom in the manufacture of the modifications on such a tool. With dressable tools, in contrast, there may be a restriction due to the contact line of the dresser.
In an alternative embodiment, both regions, and in particular both the rough machining region and the fine machining region, can be modified and have an identical orientation of the modifications. Such tools can be manufactured more easily by the dressing process in accordance with the present disclosure since the line of action of the dresser into the tool and thus the direction of the modification on the tool can hardly be changed. This admittedly results in a different orientation of the modification on the tool due to the different diagonal ratios in the two regions. Since, however, the rough machining region is anyway only used for a coarse machining and the final surface shape is only produced by the fine machining step, this can be accepted in some cases.
In this case, the modification of the rough machining region only approximately produces the desired modification on the gear teeth, with the actual modification, however, being in the permitted tolerance range. The diagonal ratio for the fine machining step is optionally selected such that the desired orientation of the diagonal ratio results. The diagonal ratio for the rough machining step is, in contrast, optionally selected such that the actual modification is in the permitted tolerance range. In this respect, the shape of the modification, e.g. the coefficient functions, can optionally be changed in the rough machining region over the fine machining region (e.g., the shape of the modification for the rough machining region may be different than the shape of the modification for the fine machining region).
In accordance with the present disclosure, the modification can also generally only approximately produce the desired modification on the gear teeth in at least one region of the tool, in particular in the rough machining region, with the diagonal ratio used. The shape of the modification and the diagonal ratio are advantageously selected such that the actual modification is in the permitted tolerance range.
In a further embodiment of the present disclosure, the tool can have at least two regions which are used successively for the machining of different regions of the workpiece. In accordance with the present disclosure, the machining in the one region can take place with a different diagonal ratio than the machining in the other region.
The tool optionally has a modified region and a non-modified region in which work is carried out with different diagonal ratios.
In this respect, the diagonal ratio in the unmodified region can be selected as smaller than in the modified region to reduce the width of the tool since the unmodified region can thus be used for machining a larger region of the workpiece and can be shorter than with a constant diagonal ratio. The larger diagonal ratio in the modified region can, in contrast, be determined by the desired orientation of the modification on the tooth flank or the desired resolution in the second direction. In another variant, the diagonal ratio in the unmodified region can be larger than in the modified region to reduce the load on the tool in this region. Such a procedure in particular makes sense when the unmodified region has to remove more material than the modified region.
In accordance with the present disclosure, it is possible to work in a region which is used for machining an upper or lower end region of the workpiece with a smaller diagonal ratio than in a region used for machining a middle region of the workpiece. For in the machining of the upper or lower end region of the workpiece, the total tool does not yet dip into the workpiece so that the loads are lower here.
In a further variant of the present disclosure, the tool can have two modified regions between which an unmodified region lies, with the regions being used consecutively for machining different regions of the workpiece. In this respect, work is optionally carried out with different diagonal ratios in the two modified regions. Different modifications, and in particular modifications with different orientations and in particular with different first directions can in particular hereby be produced in the respective regions of the workpiece. The two modified regions of the tool can have the same orientation of the modification. Alternatively, however, different orientations of the modification can also be selected here. The two modified regions can in particular be regions for machining the lower or upper edges of the workpiece.
The modified region and the unmodified region are optionally arranged such that the progression of the contact point between the tool and the workpiece is completely in the unmodified region during the machining in at least one grinding position. It is hereby ensured that a position is available at which the diagonal ratio can be varied without hereby influencing the geometry of the gear teeth on the workpiece. This is achieved in that the diagonal ratio is varied in a grinding position in which the contact point between the tool and the workpiece only sweeps over the unmodified region of the tool so that there is no modification here which would be influenced by the diagonal ratio. In this respect, work can in each case be carried out with a constant diagonal ratio in both modified regions. In this case, the diagonal ratio is kept constant for as long as the contact point between the tool and the workpiece extends through one of the modified regions.
It is, however, conceivable as an alternative to such a procedure to vary the diagonal ratio steadily, for example in a transition region between a modified region and an unmodified region. The first directions in which the modification is constant, however, hereby no longer extend in parallel with one another in this transition region.
In addition to the method in accordance with the present disclosure, the present disclosure furthermore comprises a tool for the carrying out of a method such as was described above. The tool can in particular have at least one modified region and one unmodified region which can be used successively for the machining of different regions of the workpiece. Alternatively or additionally, the tool can have two modified regions between which an unmodified region lies and which can be used successively for the machining of different regions of the workpiece. In a first variant, at least one of the modified regions has a modification of the surface geometry which can be described at least approximately in the generating pattern at least locally in a first direction of the tool by a linear and/or quadratic function, with the coefficients of this linear and/or quadratic function being formed by coefficient functions FFtC,1, FFtL,1 and/or FFtQ,1 in a second direction of the tool which extends perpendicular to the first direction. In this variant, the first direction of the tool has an angle ρFS not equal to zero with respect to the tool width direction. In a second variant which can optionally be combined with the first variant, a modification is used whose pitch and/or crowning varies in dependence on the angle of rotation of the tool and/or on the tool width position
In a possible embodiment of the present disclosure, the two modified regions of the tool can be modified differently and can in particular have modifications with different orientations. However, a modification having the same orientation in the two regions is also conceivable.
The modification may be configured such as was already shown with respect to the method in accordance with the present disclosure.
If one of the gear manufacturing machines described below is used with a conical tool, it will optionally have an input function and/or a calculation function via which different diagonal ratios and/or a variable diagonal ratio can be specified and/or determined. The input function can in particular allow different diagonal ratios to be specified in different regions and/or to specify a diagonal ratio variable over the tool width. Alternatively or additionally, the input function can allow an input of a desired modification and determines the diagonal ratios required for producing such a modification. The gear manufacturing machine furthermore optionally has a control function which varies the diagonal ratio as part of the machining of a workpiece. The control function optionally varies the diagonal ratio in an automated manner.
The control function in accordance with the present disclosure can carry out at least two machining steps which take place successively and in which a respective other region of the tool is used for the machining of the same region of the workpiece. These steps can in particular be at least one rough machining step and at least one fine machining step.
In a possible embodiment of the present disclosure, the control takes place by the control function such that the machining steps take place using different diagonal ratios. The rough machining step and the fine machining step can in particular be carried out using different diagonal ratios. A non-dressable tool can in particular be used in this respect.
Alternatively or additionally, the control function can vary the diagonal ratio at least once in the course of a machining step. In this respect, the control function can in particular vary the diagonal ratio while the tool moves over the width of the gearing of the workpiece in a machining step. The control function optionally works with different diagonal ratios for the machining of different regions of the workpiece. In this respect, a functional variant can be provided which works with a constant diagonal ratio within the respective regions. In this case, an input function is optionally provided which allows a definition of the regions and a specification of the respective diagonal ratios provided there. The control function can alternatively vary the diagonal ratio during the machining of the workpiece in dependence on the axial feed of the workpiece. The variation can in particular take place such that the diagonal ratio is given as a non-constant, optionally continuous, function of the axial feed at least in a region of the axial feed. The gear manufacturing machine optionally has an input function which allows the specification of the non-constant function.
The gear manufacturing machine further optionally has a selection option by which two or more of the different input and/or control functions shown in more detail above can be selected.
In accordance with a further aspect of the present disclosure and independently of a variation of the diagonal ratio, tool can be used in accordance with the present disclosure having a conical basic shape (e.g., a substantially conical shape).
The inventor of the present disclosure has recognized that the flexibility in the course of the diagonal feed generating machining can be improved with respect to the previously used tools having a cylindrical basic shape (e.g., a substantially cylindrical shape) by a tool which has a conical basic shape.
The tool in accordance with the present disclosure having a conical basic shape optionally has involute gear teeth which can, however, optionally have modifications. Involute gear teeth have a geometry which is produced by the generating machining step between a cylinder and a rack. The conical basic shape is produced in that the axis of rotation of the cylinder is tilted toward the main plane of the rack in the course of this generating machining step.
In accordance with an embodiment of the present disclosure, the conical angle of the tool is greater than 1, greater than 30′, or greater than 1°. Larger differences between the modifications on the right and left tooth flanks can also be produced by a correspondingly large conical angle.
Alternatively, the conical angle of the tool may be less than 50°, less than 20°, or less than 10°. This has technical production reasons, on the one hand, since the conical angle of the tool cannot be selected as any desired amount. The useful height of the tool is furthermore the smaller, the larger the conical angle of the tool with dressable tools to the extent that they are not anyway formed by grinding material applied to a conical base body.
The inventor of the present disclosure has recognized that in the case of the use of a conical tool the conical angle is available as a further degree of freedom and that specific parameters of the macrogeometry of the tool and of the machining procedure influence the modifications on the right and left tooth flanks differently in each case so that different modifications are also possible on the right and left flanks of the workpiece during two-flank machining by a corresponding selection or setting of these parameters.
The specific modification of the surface geometry of the tool is optionally produced in that the position of the dresser to the tool is varied in dependence on the angle of rotation of the tool and/or on the tool width position during dressing in addition to the delivery required by the conical angle. A variety of modifications can hereby be produced by a particularly simple method. The dressing of the tool can take place on one flank or on two flanks.
In accordance with the present disclosure, different modifications are optionally produced on the left and right tooth flanks. The degree of freedom which is given by the conical angle of the tool having a conical basic shape is optionally used for this purpose. Modifications having a different orientation are optionally produced on the left and right tooth flanks. In this respect, in particular the first direction in which the modifications are constant can differ on the left and right tooth flanks in this respect.
The present disclosure can furthermore optionally also be used to machine or generate gear teeth of the workpiece which are asymmetrical on the left and right tooth flanks.
The machining of the workpiece optionally takes place on two flanks in accordance with the present disclosure. In this case, both the left and the right tooth flanks are in contact with the tool during the gear manufacturing machining process. The two-flank generating machining has the advantage that the machining time can be substantially shortened with respect to a single-flank machining. The two-flank generating machining has the disadvantage, however, that the machining processes for the left and right flanks cannot be selected differently. It is in particular necessary for the left and right flanks to be worked with the same diagonal ratio. The provision of different modifications on the left and right tooth flanks of the workpiece is nevertheless made possible by the conical tool provided in accordance with the present disclosure.
In accordance with the present disclosure, the workpiece can have a cylindrical or a conical basic shape. In both cases, the conical tool in accordance with the present disclosure can be used.
In accordance with the present disclosure, a desired orientation of the modification on the left and right flanks is achieved by a suitable selection of the conical angle. The present disclosure in particular comprises a step of specifying a desired orientation of the modification on the left and right tooth flanks and of determining a conical angle suitable for this purpose.
In the machining process in accordance with the present disclosure, the axial feed of the tool optionally has a feed motion of the tool to the workpiece superposed on it. The superposed movement optionally takes place in the direction of the cone. It is hereby achieved that the tool has the same engagement depth into the workpiece during the machining process despite the conical base shape. The feed motion in particular takes place in linear dependence on the axial feed. The proportionality factor between the axial feed and the feed motion of the tool optionally depends on the conical angle and optionally corresponds to the tangent of the conical angle. The modifications of the dressing kinematics required for producing the modification can have this movement superposed on them.
In addition to the method in accordance with the present disclosure, the present disclosure furthermore comprises a tool for the gear manufacturing machining of a workpiece by a diagonal generating method, said tool having a conical base shape. The tool has a modification of its surface geometry which can be described at least approximately in the generating pattern at least locally in a first direction of the tool by a linear and/or quadratic function, with the coefficients of this linear and/or quadratic function being formed in a second direction of the tool which extends perpendicular to the first direction being formed by coefficient functions FFtC,1, FFtL,1 and/or FFtQ,1 and/or a modification whose pitch and/or crowning varying in dependence on the angle of rotation of the tool and/or on the tool width position. The conical angle of the tool may be larger than 1′, larger than 30′, or larger than 1° and/or the conical angle of the tool may be less than 50°, less than 20°, or less than 10°. The advantages which were already described in more detail above result from the tool in accordance with the present disclosure.
The tool is optionally a dressable tool. In a possible embodiment, the tool can have a base body on which a layer of grinding material is applied whose shape is variable by a dressing process.
In a possible embodiment, the base body can already have a conical base shape in order also to provide a uniform thickness of the available layer of grinding material even with a conical base shape of the finished tool. The present disclosure can, however, also be used with tools having a cylindrical base body on which a cylindrical layer of grinding material is applied. There is hereby greater freedom in the choice of the conical angle.
The tool in accordance with the present disclosure can in particular be a grinding worm.
In accordance with the present disclosure, the modification of the tool can be identical or at least have the same orientation on the left and right flanks. Different modifications or differently oriented modifications are then optionally produced on the right and left flanks of the workpiece only via the conical angle.
In this respect, in accordance with the present disclosure, the modification can differ on the right and left flanks of the tool. The modification can in particular have different orientations, in particular different first directions, on the left and right flanks. Alternatively or additionally, the modification on the left and right flanks can be given by different coefficient functions in the second direction. The different modifications on the left and right flanks of the workpiece which are produced by the method in accordance with the present disclosure thus result, on the one hand, from the different modifications on the right and left flanks of the tool and, on the other hand, from the conical basic shape of the tool.
If one of the gear manufacturing machines described below is to be used with a conical tool, it optionally has an input function or a determination function via which the conical angle of the tool and/or of the workpiece can be input and/or determined. The gear manufacturing machine further optionally has a control function which controls the numeric control (NC) axes of the gear manufacturing machine such that a tool having a conical basic shape rolls off on the workpiece in the diagonal generating method during the machining. In this respect, the axial feed of the tool optionally has a feed motion of the tool to the workpiece superposed on it. The superposed movement hereby resulting further optionally takes place in the cone direction. Alternatively or additionally, the gear manufacturing machine can allow the dressing of a conical tool, with the gear manufacturing machine optionally having a control function for this purpose which controls the NC axes of the gear manufacturing machine such that the dresser follows the conical basic shape on the dressing of the tool having a conical basic shape.
The gear manufacturing machine in accordance with the present disclosure can furthermore comprise an input function which allows the input of a desired modification of the workpiece. A calculation function is further optionally also provided in this case which determines the changes of the machine kinematics during dressing processes required for the production of the modifications and/or which determines the required conical angle and/or the required profile angle. In this respect, the changes of the machine kinematics which are superposed on the feed motion of the dresser to the tool specified by the conical angle can in particular be calculated. The calculation function can furthermore calculate the require diagonal ratio.
Alternatively or additionally, the gear manufacturing machine can comprise an input function by which desired modifications of the tool and/or the required conical angle and/or the required profile angle and/or the changes of the machine kinematics required for producing these modifications can be input during the dressing process. They can then, for example, be calculated externally and supplied via the input function of the gear manufacturing machine.
The gear manufacturing machine further optionally has a control function which changes the machine kinematics accordingly during the machining process and/or the dressing process.
The gear manufacturing machine in accordance with the present disclosure can in particular be equipped with a conical tool such as was described further above.
As already presented above, the tool in accordance with the present disclosure having a conical base shape can be used within the framework of a machining procedure in which the diagonal ratio is varied on the machining of a workpiece. A conical tool can, however, equally also be used when such a variation of the diagonal ratio does not take place and the diagonal ratio is at least constant for one stroke and optionally for all strokes with which the gearing is machined.
In accordance with the present disclosure, it is additionally possible to superpose further modifications on the modification of the workpiece defined in more detail above and produced by a modified surface geometry of the tool. The modification of the workpiece produced by the specific modification of the tool can in particular be superposed by a profile modification and/or a modification caused by a change of the machine kinematics during the machining process of the workpiece.
The superposition with a profile modification can already take place on the tool. The tool can in particular comprise a profile modification in addition to the above-defined modification so that the total modification of the surface geometry of the tool results as the sum of the above-defined modification and of a profile modification. It is then transmitted onto the workpiece by the diagonal generating method and optionally has a modification produced in the diagonal generating method superposed on it by a change of the machine kinematics.
In addition to the method in accordance with the present disclosure, the present disclosure furthermore comprises a gear manufacturing machine for machining a workpiece using a tool in the diagonal generating method and/or for dressing a tool using a dresser in line contact for carrying out a method such as was described in more detail above.
The gear manufacturing machine can comprise a manufacturing machine with which a workpiece received in a workpiece holder can be machined by a tool received in a tool holder. The tool holder is optionally arranged at a machining head which has corresponding axes of movement for producing a relative movement between the tool and the workpiece for machining the workpiece. The workpiece holder and the tool holder each have axes of rotation whose movements can be coupled with one another to carry out the generating machining.
The gear manufacturing machine can comprise a dressing machine. It optionally has a dresser holder via which the dresser can be rotated about an axis of rotation. The dressing machine further optionally has a tool holder into which the tool is clamped and via which the tool can be rotated about its axis of rotation. Axes of movement are furthermore provided via which the relative movements required for the dressing in accordance with the present disclosure can be produced between the dresser and the tool.
The gear manufacturing machine in accordance with the present disclosure is particularly optionally a combination of a manufacturing machine and a dressing machine. The dressing machine and the manufacturing machine optionally shape the tool holder. In this case, a tool clamped in the tool holder can be used, on the one hand, to machine a workpiece. It is furthermore possible to dress the tool clamped in this tool holder without the tool having to be unclamped and clamped in another tool holder again.
The axes of movement of the gear manufacturing machine are optionally NC axes. The gear manufacturing machine optionally has a control for controlling the NC axes of the gear manufacturing machine. The control is optionally programmed such that a method in accordance with the present disclosure can be carried out on the gear manufacturing machine. The control in particular has functions for carrying out a method in accordance with the present disclosure.
The gear manufacturing machine in accordance with the present disclosure optionally has an input function via which a desired modification of the surface geometry of the workpiece can be specified. The gear manufacturing machine furthermore optionally has a control function which determines the modification of the surface geometry of the tool suitable for providing the modification of the surface geometry of the workpiece and a suitable diagonal ratio.
The control function optionally produces the modification of the surface geometry of the tool during dressing, in particular by a corresponding control of the axes of movement of the dressing machine. Alternatively or additionally, the control function can carry out the diagonal generating method for machining the workpieces with the diagonal ratio suitable for producing the desired modification of the surface geometry of the workpiece.
The gear manufacturing machine can furthermore have a dressing function for the modified dressing of the tool which varies the position of the dresser with respect to the tool during dressing in dependence on the angle of rotation of the tool and/or on the tool width position. The dressing function optionally sets at least the engagement depth and the pressure angle of the dresser in dependence on the angle of rotation of the tool and/or on the tool width position, in particular as a variable function of the angle of rotation of the tool and/or of the tool width position. Alternatively or additionally, the dressing function can utilize at least three and optionally four or five degrees of freedom of the gear manufacturing machine in the relative positioning between the dresser and the tool for producing the desired modification. The degrees of freedom are optionally controllable independently of one another for producing the desired modification.
The input function can be configured in accordance with the present disclosure such that it allows the specification of the desired modification of the surface geometry of the workpiece as a continuous function and/or on a scatter plot. The continuous function is optionally specifiable on a surface on the tooth flank and/or the scatter plot spans a surface on the tooth flank. Provision can in particular be made that the desired variation is specifiable over the total tooth flank.
In accordance with a possible embodiment of the present disclosure, the input function can allow the specification of the desired modification of the surface geometry of the workpiece at at least two or three rolling angles as a function of the workpiece width position and can carry out an interpolation for the rolling angle regions disposed therebetween.
The gear manufacturing machine optionally determines the modification of the surface geometry of the tool which is necessary for producing the desired modification of the surface geometry of the workpiece as a continuous function and/or on a scatter plot. Alternatively or additionally, the gear manufacturing machine can allow the specification of the modification of the surface geometry of the tool as a continuous function and/or on a scatter plot.
The continuous function is optionally determined on a surface over the tooth flank and/or is specifiable on this. Alternatively or additionally, the scatter plot can span a surface on the tooth flank. The modification can in particular be determined on the total tooth flank and/or is specifiable on it.
The modification of the surface geometry of the tool is optionally variable within the framework of the determination and/or specification at at least two or three rolling angles as a function of the tool width position, with the control carrying out interpolation for the rolling angle regions disposed therebetween.
Provision can furthermore be made that the gear manufacturing machine allows the specification of a desired modification of the surface geometry of the workpiece as a function which can be described at least approximately in the generating pattern at least locally in a first direction of the workpiece by a linear and/or quadratic function, with the coefficients of this linear and/or quadratic function being formed in a second direction of the workpiece which extends perpendicular to the first direction by coefficient functions FFtC,2, FFtL,2 and/or FFtQ,2, with the coefficient functions FFtl,2 and/or FFtll,2 and/or the first direction of the modifications of the surface geometry of the workpiece optionally being freely variable and/or selectable at least within certain conditions. The input function can in particular include corresponding input fields for inputting data from which the coefficient functions and/or the first direction are determined within the control and/or by which they are determined.
The gear manufacturing machine can furthermore allow the specification of a desired modification of the surface geometry of the workpiece as a function which has a pitch and/or crowning in a first direction which varies in the workpiece width direction, i.e. in a second direction. Corresponding input fields can in particular be provided for this purpose within the input function via which the pitch and/or crowning can be defined as a function of the workpiece width direction.
In accordance with a possible embodiment of the present disclosure, the modification of the surface geometry of the workpiece can be specifiable at at least two or three rolling angles as a function of the tool width position, with the control carrying out interpolation for the rolling angle regions disposed therebetween. The pitch of the modification can be specified by the specification at two rolling angles; the crowning by the specification at three rolling angles.
Provision can furthermore be made that the gear manufacturing machine allows the specification and/or determination of a modification of the surface geometry of the tool as a function which can be described at least approximately in the generating pattern at least locally in a first direction of the tool by a linear and/or quadratic function, with the coefficients of this linear and/or quadratic function being formed in a second direction of the tool which extends perpendicular to the first direction by coefficient functions FFtC,1, FFtL,1 and/or FFtQ,1, with the coefficient functions FFtC,1, FFtL,1 and/or FFtQ,1 of the modification of the surface geometry of the tool being freely selectable and/or variable at least within certain conditions. The corresponding coefficient functions can in particular be variable within the framework of curve fitting to determine a modification of the tool which produces the desired modification of the workpiece in the best possible manner. The coefficient functions can, however, optionally also be determined by the control analytically from the data which were input for the desired modification of the workpiece.
Provision can furthermore be made that the gear manufacturing machine allows the specification and/or determination of a modification of the surface geometry of the tool as a function which has a pitch and/or crowning in a first direction which varies in the direction of the workpiece width.
The modification of the surface geometry of the tool can in particular be specifiable and/or variable within the framework of the determination and/or specification at at least two or three rolling angles as a function of the workpiece width position, wherein the control carries out interpolation for the rolling angle regions disposed therebetween.
The gear manufacturing machine in accordance with the present disclosure and the functions in accordance with the present disclosure are optionally configured such that they implement the methods described in more detail above, which allow the inputs shown above and/or which carry out the determinations or controls shown above.
The present disclosure furthermore comprises a computer program having an input function for inputting data on a desired modification of the surface geometry of the workpiece and having a function for determining the modification of the tool and of the diagonal ratio, with the functions implementing a method such as was shown above. The computer program can in particular have the functions which were shown above with respect to the functions of the gear manufacturing machine.
The computer program can optionally be installed on a gear manufacturing machine to be able to carry out a method in accordance with the present disclosure using the gear manufacturing machine. Alternatively, the computer program can have an output function for data for use on a gear manufacturing machine, and/or the computer program can have an interface with the gear manufacturing machine.
Some features will be described again in the following which relate to all aspects of the present disclosure:
The generating machining method in accordance with the present disclosure is optionally a generating grinding method. The tool which is dressed or used in accordance with the present disclosure is optionally a grinding worm.
The method in accordance with the present disclosure and the apparatus or tools in accordance with the present disclosure are optionally configured such that an involute gearing is produced in accordance with the present disclosure on the workpiece. The modifications of the surface geometry of the tool and/or of the workpiece which are used or which can be produced in accordance with the present disclosure are therefore optionally modifications of an involute surface geometry.
With respect to the function defined in accordance with the present disclosure which at least approximately describes the modification of the tool or of the workpiece and which can be described at least approximately in the generating pattern in a first direction by a constant, linear and/or quadratic function, with the coefficients of this constant, linear and/or quadratic function being formed in a second direction which extends perpendicular to the first direction by coefficient functions FFtC,1/2, FFtL,1/2 and/or FFtQ,1/2, FFtC,1/2 can be the coefficient function for the constant portion, FFtL,1/2 can be the coefficient function for the linear portion and FFtQ,1/2 can be the coefficient function for the quadratic portion of the modification of the tool or of the workpiece in the first direction.
FFtC,1/2 is optionally non-constant and further optionally depends non-linearly on the position in the second direction. FFtL,1/2 is furthermore optionally non-constant and further optionally depends linearly or non-linearly on the position in the second direction. FFtQ,1/2 can be equal to zero or can be constant in a first embodiment of the present disclosure. In a second embodiment, FFtQ,1/2 can be non-constant and can optionally linearly or non-linearly depend on the position in the second direction.
The modification of the workpiece or of the tool in the generating direction can optionally be described not only locally, but also at least in a part region of the gearing and optionally also globally over the total gearing at least approximately by the constant, linear and/or quadratic function which may have been specified in more detail above, with the coefficients of this constant, linear and/or quadratic function being formed in a second direction which extends perpendicular to the first direction by coefficient functions FFtC,1/2 for the constant function and FFtL,1/2 for the linear portion and/or FFtQ,1/2 for the quadratic portion.
If it is stated in the present application that a modification can be described at least approximately by a specific function, this optionally means that the specific function describes the modification within the framework of a specified permitted tolerance and/or that the difference between the specific function and the modification lies within a specified permitted tolerance range. The method in accordance with the present disclosure can include the step of specifying a permitted tolerance and/or a permitted tolerance range. The gear manufacturing machine in accordance with the present disclosure or the computer system or computer program can furthermore comprise a function for specifying a permitted tolerance and/or a permitted tolerance range.
The present disclosure will now be explained in more detail with reference to embodiments and to drawings.